The present invention relates to a dielectric resonator antenna having three separate and mutually orthogonal feeds such that separate beams can be formed with different polarisations and such that the polarisation of an incoming beam can be measured.
Since the first systematic study of dielectric resonator antennas (DRAs) in 1983 [LONG, S. A., McALLISTER, M. W., and SHEN, L. C.: “The Resonant Cylindrical Dielectric Cavity Antenna”, IEEE Transactions on Antennas and Propagation, AP-31, 1983, pp 406–412], interest has grown in their radiation patterns because of their high radiation efficiency, good match to most commonly used transmission lines and small physical size [MONGIA, R. K. and BHARTIA, P.: “Dielectric Resonator Antennas—A Review and General Design Relations for Resonant Frequency and Bandwidth”, International Journal of Microwave and Millimetre Wave Computer-Aided Engineering, 1994, 4, (3), pp 230–247]. Most of the configurations reported have used a slab of dielectric material mounted on a ground plane excited by either an aperture feed in the ground plane or by a probe inserted into the dielectric material.
A few publications have reported experiments using two probes fed simultaneously in a circular cross-section dielectric slab. These probes were installed on radials at 90° to each other and fed in anti-phase so as to create circular polarisation [MONGIA, R. K., ITTIPIBOON, A., CUHACI, M. and ROSCOE D.: “Circular Polarised Dielectric Resonator Antenna”, Electronics Letters, 1994, 30, (17), pp 1361–1362; and DROSSOS, G., WU, Z. and DAVIS, L. E.: “Circular Polarised Cylindrical Dielectric Resonator Antenna”, Electronics Letters, 1996, 32, (4), pp 281–283.3, 4] and one publication included the concept of switching the probes on and off [DROSSOS, G., WU, Z. and DAVIS, L. E.: “Switchable Cylindrical Dielectric Resonator Antenna”, Electronics Letters, 1996, 32, (10), pp 862–864].
The general concept of deploying a plurality of probes within a single dielectric resonator antenna, as pertaining to a cylindrical geometry, is described in the paper KINGSLEY, S. P. and O'KEEFE, S. G., “Beam Steering and Monopulse Processing of Probe-Fed Dielectric Resonator Antennas”, IEE Proceedings—Radar; Sonar and Navigation, 146, 3, 121–125, 1999, the disclosure of which is incorporated into the present application by reference.
It is known from N Inagaki: “Three-dimensional corner reflector antenna”, IEEE Transactions on Antennas and Propagation, Vol. AP-22, no. 7, July 1974 (1974–07), pp 580–582 to provide a reflector antenna having three mutually orthogonal planar reflectors and a unipole radiator mounted on one of the reflectors.
U.S. Pat. No. 3,662,260 discloses a probe for sensing orthogonal components of an electric field, the probe comprising a body made of a dielectric material and having mutually orthogonal passageways bored therein to receive electrode assemblies.
U.S. Pat. No. 2,872,675 discloses a radar reflector for use in radar systems comprising a conductive corner reflector filled with a dielectric material.